Description
The Metropolitan Water Reclamation District of Chicago authorities described the 30′ deep brick manhole as “the worst manhole in Chicago”, and that all other manhole rehabilitation products had refused to attempt to fix. The manhole provided access to a 15′ diameter trunk line. The manhole had lost all three layers of brick in some areas and much mortar and bricks throughout due to bacteriological hydrogen sulfide attack, leaving the manhole possibly unsound.

A Raven Certified Applicator, robotically videoed, water blasted, then used spincast equipment to apply a 1.5″ thick high early strength, fiber-reinforced mortar. This first layer was allowed to set eight hours before a second 1.5″ layer was spincasted. After the second mortar layer was applied, the first man entered the hole and trowel finished the mortar, performed structural patchwork and stopped leaks. 16 hours later the manhole was sprayed with 125 mils of Raven 405 to prevent future corrosion and provide additional structural enhancement.